The invention relates to a device for making seams on three-dimensional objects made of materials such as textile woven materials, leather, synthetics or similar materials. Such devices are used for the production of clothing, upholstery for seating furniture and automobiles, and for the production of shoes.
Usually, three-dimensional objects such as envelopes made of fabric are manufactured in such a way that pre-made two-dimensional cuttings are sewn lying flat on top of each other with a sewing machine. The two cuttings are sewn together at an exactly specified distance from the cutting edges. Beforehand, the cuttings have been provided with markings which have to match during sewing, and it is also necessary to displace the cuttings relative to each other during sewing. Joining of the cuttings by means of a sewing machine is very time-consuming and requires a high degree of routine of the operator who has to guide the cuttings and operate the sewing machine. Because of the relatively slow manual control, the performance possibilities of the sewing machine are not fully utilized. The feeding of the materials is made by the sewing machine intermittently between the penetration movements of the needle. From DE 33 38 405 A1, a device for producing three-dimensional articles provided with seams is known wherein a sewing machine is attached to a manipulator in the form of a robot arm. This sewing machine is moved by the manipulator in such a manner that said sewing machine is guided along the intended seam line of the two cuttings to be sewn. An under-thread bobbin grips underneath the cuttings to be sewn and a presser presses against the top cutting. The lower cutting is supported by a brush bed through which the under-thread bobbin moves.
A similar sewing device is known from EP 0 344 400 A1. Here, too, a sewing machine is secured to the manipulator arm of a robot, the details of which sewing machine, however, are not described.
The known devices on which a sewing machine is moved by a manipulator in a three-dimensional system involve the difficulty of obtaining a neat and distortion-free seam and still carrying out the sewing action at high working speed.